This invention generally relates to a green-sand molding process. More particularly, this invention relates to a method and system for operating a green-sand molding machine to produce a mold that has the desired charging of green sand.
Typically, in a green-sand molding process in, e.g., a green-sand molding machine with a flask, an insufficient charge of green sand in the flask is detected after a mold has been actually produced. Thus, to change or improve its bulk density, many repeated trials for molding have had to be made. Simultaneously, data such as on the configuration of a pattern plate, conditions of molding (e.g., the pressure of the squeezing), and the physical properties of the green sand, have had to be modified. For a particular pattern plate or its varieties that are commonly used, with empirically-accumalated data on the, to same extent an optimum mold is produced.
However, the empirically-accumulated data is of no use for a new application, e.g., for a new pattern plate that has a very different configuration from a common one, or a new molding process, or new green sand that has different physical properties from a common one. Consequently, to obtain the optimum conditions for such a new application, many trials for molding must be carried out, and this takes many hours. Further, when a mold is produced, the influence of bentonite or oolite must be considered, and such an influence cannot be predicted from the ordinary charging of the particles of the green sand.
The embodiments of the present invention are directed to resolve the above problems.
One object of the invention is to provide a method for operating a given green-sand molding machine with the aid of a computer that produces a mold that has a desired charging of green sand and that requires no actually-produced mold for detecting the charging of the green sand.
Another object of the invention is to provide a system for a green-sand molding process that can determine the desired charging of green sand in a mold to be molded, before it has been actually produced.
In the present invention, the types of green-sand molding processes used in the green-sand molding machine include a molding process by the so-called xe2x80x9cjolt squeezingxe2x80x9d with a solid material (e.g., a squeezing board), pressurized air or air impulses, and a combination of these processes.
In the present invention, the term xe2x80x9cdesign condition of pattern platexe2x80x9d incorporated in the green-sand molding machine includes items such as the location(s) of vent plug(s), the number of vent plug(s), and the shape or height of a pocket(s).
In the present invention, the term xe2x80x9cgreen-sand moldxe2x80x9d generally means a mold in which green sand composed of silica sand, etc. as aggregates, and a binder, e.g., bentonite or oolite, is used.
In the present invention, the term xe2x80x9cphysical properties of the green sandxe2x80x9d of the green sand that is incorporated in the green-sand molding machine generally means properties such as water content, compressive strength, and permeability.
In the present invention, the term xe2x80x9cpressure of squeezingxe2x80x9d generally means a pressure where the green-sand molding machine presses the green sand within a flask. The pressure of the squeezing generally is caused by a solid material. However, it is to be noted that the pressure of the squeezing also includes a pressure caused by such as air, e.g., shock waves of pressurized air or a blast from an explosion. In this case, the so-called xe2x80x9cpressurized-air-applyingxe2x80x9d or xe2x80x9cair blowingxe2x80x9d-types of molding processes are used.
In the present invention, analyzing a green-sand molding process includes a finite element method, a finite volume method, differential calculus, and a discrete element method.